The present invention relates to an interface for coupling a standard telephone to a computer for internet telephony.
Based on the increasing use of personal computers (PC's) and the internet, a new communications medium is in use. Known as Internet Telephony, Computer Telephony or VOIP (voice over internet protocol), it allows users to communicate with one another using standard personal computers connected to the internet through Internet Service Providers. The communication can include voice (audio), data and video. Voice communication over the internet can be achieved computer-to-computer, computer-to-phone, or phone-to-phone.
To facilitate this new form of communication, new services and software products such as Net2phone™, Netmeeting™, Dialpad™ and many others are now available. When a call is placed from and/or received by a personal computer, the voice signal normally travels via the computer's sound card or equivalent.
The most common user interface available for PC voice communication is a microphone and loudspeakers, which usually connect to the sound card or equivalent in a personal computer. A user talks into the microphone, and listens through the loudspeakers.
Because the microphone senses both the voice of the user and the sound coming from the speakers, and because the internet connection usually introduces some finite delay in transmission, a user may hear the echo of his own voice. To mitigate this annoyance, some users make use of a headset instead of loudspeakers and microphone. The headset connects to the PC sound card in place of the microphone and speakers. Use of a headset does not prevent the headset user from hearing his own echo, but it reduces the echo for the other user. If both users in a connection use headsets, echo is reduced for both.
While the use of headsets ran reduce echo, they may not be the communications devices of choice for many people. For those PC users who would like to use a standard telephone, including a cordless phone, there is no existing simple and inexpensive interface device allowing interconnection between a telephone and a personal computer sound card while satisfactorily eliminating echo. For those users who prefer to use a headset, the use of this invention with a cordless telephone allows a standard headset to be used as a cordless headset.
Two products have been recently introduced to the market for the purpose of connecting a standard telephone to a PC under the tradenames Internet Phonejack™ and Hi-Phone™. Both of these products connect to a standard analog telephone, but do not provide an analog output to the PC. Both products digitize the telephone signal before passing it to the PC. The Internet Phonejack™ is a plug-in card that is installed into the PC data bus. The data bus is strictly digital, and has no provision for the connection of an analog signal. The Hi-Phone™ is external to the PC, but communicates with it via a digital serial port connection.
Both of these products have analog-to digital and digital-to-analog signal processing functions between the telephone and PC. Because both of these products communicate with the PC in digital formats, both require the installation of additional software drivers in the PC.